Conventionally, when displaying images of measured target objects (echo images) on a display screen, radar devices suppress echoes which are not generated continuously at the same location (sea clutters, etc.), and perform scan-to-scan correlation processing for emphasizing echoes of the target objects (see JP11-352212A).
However, since an echo level varies according to conditions of a transmission pulse, problems such as a contour of a target object fades even if a scan-to-scan correlation is performed may arise. In particular, because weighted addition processing is performed in the technique of JP11-352212A, contours of stationary target objects may also fade due to changes, errors or the like of echo levels of movable target objects.